Mattress spring unit construction

ABSTRACT

An improved mattress inner spring unit having a plurality of coil springs arranged in rows with each coil spring being comprised of a series of convolutions. Each coil spring terminates in end convolutions which have offset portions formed thereon. The coil springs are arranged in the inner spring unit so that the offset portions extend into overlapping relation with adjacent offset portions. Such an arrangement allows the coil springs to be secured together by spirally rotating a helical coil across each of the rows so as to interlace the offset portions. The helical coils are thus positioned in both the upper and lower surfaces of the inner spring unit. When all adjacent offset portions have been interlaced with the helical coils, the end portions of each helical coil are compressed around the overlapped offset portions of the outermost row of coil springs.

[ 51 Apr. 4, 1972 United States Patent Davis Primary ExaminerCasmir A.Nunberg Attorney-Hume, Clement, Hume & Lee

[541 MATTRESS SPRING UNIT CONSTRUCTION ABSTRACT spring unit having aplurality of with each coil spring being comtions. Each coil springterminates h have offset portions formed e arranged in the inner springunit rs ew m n .m m .mO md f H8 mm d m em m nf P m um ii or AcP m o 7 C.d m3 ,1 .W w 8 u e SA a H.. .w SB H AF NH 72 in end convolutions whicthereon. The coil springs at so that the offset portions with adjacentoffset portion coil springs to be secured to 211 App]. No.: 63,588

extend into overlapping relation 5. Such an arrangement allows thegether by spirally rotating a helical as to interlace the offsetporpositioned in both the upper spring unit. When all adjacent l lies/04, A47c 25/00 .5/260, 267, 269, 270, 351

[5 1] Int. Cl.

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coil across each of the rows so References and trons. The helical COllSare thus and lower surfaces of the inner ofiset portions have beeninterlaced with the helical coils, the end portions of each helical coilare compressed around the 5/269 X overlapped offset portions of theoutermost row of coil ......5/269 springs ...5/267 X S m T m N m. E L" Ta" A r.. e P n s W. 6 mew A um T w S 6. D GLS E n 684 N 636 U 999 H 939060 625 4 9 6 4 1 323 3 Claims, 2 Drawing Figures MATTRESS SPRING UNITCONSTRUCTION This invention relates to improvements in mattress innerspring units and, more particularly, to the cross helical coil structurefor mattress inner spring units.

For the most part, the mattress inner spring units are formed of aplurality of interconnected coil springs arranged in side by siderelation in a plurality of parallel rows between upper and lower borderwires which are connected to the external coil springs, usually by meansof helical wires, to provide the coil spring assembly. It has been thepractice to interconnect the coil springs with a plurality of parallelhelical coils extending transversely across each of the rows in both theupper and lower surfaces of the unit. The coil springs areinterconnected by rotating each helical coil spirally about its majoraxis until it is extended across each of the rows interlacingoverlapping portions of the adjacent coil springs. However, once thehelical coils are in position they have a tendency to spin-out. (Helicalspin-out is a commonly used term in the bedding field referring to thehelical coil unwinding from the inner spring unit.) To eliminate thisaction, it has been the practice to give each end of the helical coil areverse twist, which is the doubling back of the end portion of the coilon itself, thus creating obstructions that prevent the helical coil fromunwinding from the inner spring unit.

It has also been the prior practice to strengthen the interconnectedcoil springs by crimping, which comprises reducing the diameters of theinterlaced portions of the helical coils to approximately the samecross-sectional area as the overlapping portions of the coil springs, asshown for example in U.S. Pat. No. 2,111,026. However, the prior artpractice of crimping at every point where the coil springs overlapgreatly inhibits the action of the coils and thus, reduces resiliency.

It is therefore an object of the present invention to provide a mattressinner spring unit which contains helical coils where the diameter ofeach helical coil is reduced at only the overlapping portions of theoutermost rows of coil springs so as to eliminate helical spin-out andstiffen the sides, but not the head and foot, of the inner spring unit.

It is another object to provide an inner spring unit of this type thatallows full action and resiliency of all inner coil springs.

It is a further object to provide an inner spring unit of this type thatmaintains better body conformity.

The foregoing and other objects are realized in accord with theinvention by providing a generally rectangular mattress inner springunit comprising a plurality of coil springs arranged in rows so thatadjacent portions of each coil spring overlap. The coil springs are tiedtogether by spirally rotating helical coils across each of the rows tointerlace the overlapping portions of the coil springs in both the upperand lower surfaces of the inner spring unit. The end portions of eachhelical coil are compressed at the overlapped portions of the outermostrow of coil springs. The compression reduces the diameter of the helicalcoil to approximately the same cross-sectional area as the overlappedportions so that the overlapped portions are held in a non-hingingposition. The outermost row of coil springs are thus stiffened andhelical spin-out is eliminated.

FIG. 1 is a fragmentary plan view of an inner spring unit embodying thefeatures of this invention;

FIG. 2 is a fragmentary plan view of the inner spring unit of FIG. 1taken along line 22 ofFIG. 1.

Referring now to the drawings, and more particularly to FIG. 1, there isillustrated a mattress inner spring unit embodying the features of thepresent invention and indicated generally by reference numeral 4. Theinner spring unit 4 includes a plurality of coil springs 6 arranged inrows with each coil spring 6 being comprised ofa series of convolutions.Each coil spring 6 terminates in end convolutions 9 which have opposedoffset portions 8 formed thereon. The coil springs 6 are positioned sothat the offset portions 8 extend into overlapping relation withadjacent offset portions 8. Such an arrangement allows the coil springs6 to be secured together by spirally rotating a helical coil 10 acrosseach of the rows so as to interlace the offset portions 8. The helicalcoils 10 are thus positioned in both the upper and lower surfaces of theinner spring unit 4. When all adjacent offset portions 8 have beeninterlaced with the helical coils 10, end portions 12 of each helicalcoil 10 are compressed around the overlapping offset portions 8 of theoutermost row of coil springs 6. The compression of the end portions 12reduces the coil diameter to approximately the same cross-sectional areaas the offset portions 8 so that the offset portions 8 are frictionallyengaged.

Considering now the mattress inner spring unit 4 in more detail, andreferring to FIGS. 1 and 2, the inner spring unit 4 includes a pluralityof coil springs 6 arranged in side by side relation in a plurality ofparallel rows. Each coil spring 6 is preferably tapered from its endstoward the middle so that intermediate convolutions will be of smallerdiameter than end convolutions 9. Only one end convolution 9 isindicated in the drawing as the other end convolution is identical withit. Each end convolution 9 is formed to be generally circular in shapewith the exception of two offset portions 8. The offset portions 8 arepreferably U-shaped and are formed so as to be directly opposite eachother on each convolution 9. When the coil springs 6 are properlypositioned in the inner spring unit 4 so as to be in rows, the offsetportions 8 extend to overlap ad jacent offset portions 8. The coilsprings 6 can thus be secured together by spirally rotating helicalcoils 10 across each of the rows in a conventional manner so as tointerlace the overlapping offset portion 8. The helical coils 10 are ofrelatively small diameter in comparison to the end convolutions 9 butare sufficiently large to be interlaced with the offset portions 8, thusholding the coil springs 6 together in both the upper and lower surfacesof the inner spring unit 4.

Each end portion of the helical coils 10, designated by referencenumeral 12, is compressed by any suitable means, such as a pair of dies,so that the offset portions 8, on the outermost coil springs 6, are heldagainst relative hinging movement. The compression of the helical coils10 at their ends 12, as shown in FIG. 2 of the drawings, reduces thediameter of this portion of the helical coil 10 so that it isapproximately the same cross-sectional area as the overlapping offsetportions 8. This deformation of the helical coil 10 eliminates thetendency of the helical coil 10 to spin out of the inner spring unit 4,and arrests the hinging action of the overlapping offsets 8 byfrictionally engaging them. In this manner, the outermost rows of coilsprings 6 are stiflened while the inner rows of coil springs 6 areallowed full hinging action to provide for better body conformity andmore resiliency.

It will be understood that changes may be made in the details ofconstruction, arrangement and operation without departing from thespirit of the invention, especially as defined in the following claims.

I claim:

1. In a generally rectangular mattress inner spring unit, a springstructure comprising:

a. a plurality of coil springs arranged in side by side relation in aplurality of parallel rows defining upper and lower surfaces of saidunit;

b. offset portions formed on each end of said springs extending so as tooverlap adjacent offset portions;

c. helical coils extending across each of said rows in said upper andlower surfaces and coiling about said overlapping offset portions sothat adjacent springs are interconnected, each of said helical coilsbeing deformed only on the end portions, said deformed end portionsfrictionally engaging offset portions located on the outermost rows ofcoil springs so that said offset portions are held in a non-hingingposition; and

01. said deformed end portions being compressed so as to distort thediameter of said helical coil.

2. In the generally rectangular mattress inner spring unit of claim 1wherein said offsets are U-shaped.

3. In a generally rectangular mattress inner spring unit, a springstructure comprising:

are interconnected, each of said helical coils being deformed only onthe end portions; and

d. said deformed end portions being compressed so as to distort thediameter of said helical coil and said deformed end portionsfrictionally engaging offset portions located on the outermost rows ofsaid coil springs so that said offset portions are held in a non-hingingposition.

1. In a generally rectangular mattress inner spring unit, a springstructure comprising: a. a plurality of coil springs arranged in side byside relation in a plurality of parallel rows defining upper and lowersurfaces of said unit; b. offset portions formed on each end of saidsprings extending so as to overlap adjacent offset portions; c. helicalcoils extending across each of said rows in said upper and lowersurfaces and coiling about said overlapping offset portions so thatadjacent springs are interconnected, each of said helical coils beingdeformed only on the end portions, said deformed end portionsfrictionally engaging offset portions located on the outermost rows ofcoil springs so that said offset portions are held in a non-hingingposition; and d. said deformed end portions being compressed so as todistort the diameter of said helical coil.
 2. In the generallyrectangular mattress inner spring unit of claim 1 wherein said offsetsare U-shaped.
 3. In a generally rectangular mattress inner spring unit,a spring structure comprising: a. a plurality of coil springs arrangedin side by side relation in a plurality of parallel rows defining upperand lower surfaces of said unit; b. U-shaped offset portions formed oneach end of said springs extending so as to overlap adjacent U-shapedoffset portions; c. helical coils extending across each of said rows insaid upper and lower surfaces and coiling about said overlappingU-shaped offset portions so that adjacent springs are interconnected,each of said helical coils being deformed only on the end portions; andd. said deformed end portions being compressed so as to distort thediameter of said helical coil and said deformed end portionsfrictionally engaging offset portions located on the outermost rows ofsaid coil springs so that said offset portions are held in a non-hingingposition.